Board Thread:Pokémon Help/@comment-27023030-20180201040651/@comment-27535813-20180201085834

For your first question: There is no difference in training a 5x31 and 6x31 Pokemon, just that the 5x31 Pokemon is missing out a stat on 31 IVs.

To answer your second question: I'm not sure how it will take, but certainly long since it's not guaranteed to give you 6x31 and that even with Destiny Knot on, you may be unlucky enough for the Destiny Knot to take the non-31 IVs on the stat that each parent has. You can try using an IV breeding calculator like https://mkwrs.com/destiny_knot/ to find out the chances of getting a 6x31 Pokemon.

Lastly, to answer your 3rd question, it depends on what you need. Personally, I feel that you should just stick with 5x31, even if one of its stats doesn't have 31. For clarification, let's take an example. E.g. Gengar. Gengar doesn't use it's Attack stat so it doesn't matter if it doesn't get 31 IVs on it. So a 5x31 with all of the required stats bar Attack stat works. The same goes for Infernape(which is what you want to get). If you're running a Physical Attacking or a Special Attacking set then having non-31 IVs on the Sp.Atk or Atk stat respectively does not matter since you don't plan on using said stats. If you're running mixed attacking set and still need 31 IVs in speed for Infernape, then yes you'd want to have 31 IVs in Attack and Sp.Atk. Of course, this means that you may prefer to get 6x31 IVs since you'd want to keep the bulk, but if the Infernape is running mixed and you need speed, you'd use a nature that increases Atk/Sp.Atk and decreases bulk. This means that even if you have a non-31 IVs in the def or sp.def stat, it doesn't matter. There can also be other cases where if you're a slow bulky mixed attacker, in which your nature decreases Speed and a slow Speed stat doesn't matter, so you can run non-31 IVs on that stat as well.